// Copyright 2015 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library fuchsia.ui.viewsv1;

using fuchsia.sys;

// A view is a graphical user interface component which is responsible
// for drawing and supporting user interactions in the area of the screen
// that it occupies.
//
// A view may also act as a container for other views (known as the
// view's children) which it may freely layout and position anywhere
// within its bounds to form a composite user interface.  The hierarchy
// of views thus formed is called a view tree.
//
// LIFECYCLE
//
// Use |ViewManager.CreateView()| to create a view.  The application
// uses the |View| interface to manage the view's content and implements
// the |ViewListener| interface to handle events.
//
// To destroy a view, simply close the |View| channel.
//
// ADDING CHILD VIEWS
//
// Use |GetContainer()| to obtain an interface for manipulating child views.
//
// See |ViewContainer| for more information.
protocol View {
    // Gets a service provider to access services which are associated with
    // the view.
    // The view service provider is private to the view and should not be
    // shared with anyone else.
    GetServiceProvider(request<fuchsia.sys.ServiceProvider> service_provider);

    // This is a way for an app to offer services that are associated with a
    // particular view. Used to expose services to the compositor
    //
    // In particular this should be used to let know which view is implementing
    // the ability to show an IME
    //
    // |service_names| should contain a list of service names as defined with the
    // FIDL syntax [Discoverable]
    //
    // The list of services will be used by the compositor to filter service
    // providers when looking for a particular service.
    OfferServiceProvider(fuchsia.sys.ServiceProvider service_provider,
                         vector<string> service_names);

    // Gets an interface for managing the view's children.
    GetContainer(request<ViewContainer> container);
};

// An interface clients may implement to receive events from a view.
protocol ViewListener {
    // Called when the view receives new properties from its ancestors.
    // Initially the view has no properties so this method will be called
    // as soon as properties first become available and whenever they change
    // thereafter.
    OnPropertiesChanged(ViewProperties properties) -> ();
};